Stripper



I Feb. 7, 1939.

A. L. LEMAN STRIPPER Filed Jan. 30, 1936 2 Sheets-Sheet 1 IN VENTOR. A IBY 4Mzz/ c.

40% ATTORNEY.

. AQL. LEMAN Feb. 7, 1939.

STRIPPER Filed Jan. 30, 19:56

2 Sheets-Sheet 2 Patented Feb. 7, 1939 UNITED STATES STRIPPEBArthurLLeman, Houston, Tex, adgnorto The National Supply Company,Pittsburgh, Pa, a

corporation of Pennsylv Application January :0, 193s, sci-m No. 01,402

2 Claims. (01. ass-1) My invention relates generally to casing heads andmore specifically to casing heads having embodied therein a tubingstripper arranged to seal an inner concentric string of tubing in acasing head.

This invention may be conveniently applied to casing heads for use inthe oil well art and is more particularly adapted to seal ofl an innerconcentric string of tubing which is suspended from within the casinghead from a point thereabove.

A tubing stripper in the casing head art comprises an annular flexiblemember held in position within the casing head, or similar member, insuch a manner as to prevent the passage of fluid therebetween. Thisannular flexible member depends inwardly and downwardly, contacting theouter surface of the inner string of casing. By reason of its shape thestripper provides an inherent initial pressure against the tubing whichaids in effecting a seal therebetween. Again any fluid well pressureacting upon the lower surface of the stripper increases the pressureengagement between the stripper and the tubing, thereby developing agreater sealing engagement in proportion to the existing pressure.

The stripper is purposely made of flexible material to provide for thepassage of the tubing therethrough which prevents the escape of thefluid within the well even though couplings of enlarged diameterconnecting the sections of tubing must pass through the stripper.

The principal object ofthis invention is the provision of a flexiblestripper that will withstand the repeated passage of enlarged couplingmembers and the like without endangering the emciericy of the sealthereof. This advantage is gained by the particular design of thestripper member and the manner in which'it is incorporated into thecasing head structure.

The specific objects of this invention deal with the manner in which thestripper is formed, the manner in which it is locked in place, themanner of forming the annular flexible hinge, the manner of supportingthe hinged portion and the mode of backing the hinged portion to give itinherent rigidity without endangering its flexibility. 7

Other objects and advantages will appear in the following specification.

In the accompanying drawings wherein I have shown a practical embodimentofthe principles of my invention, v

Fig. 1 is a vertical sectional view of a casing head having the stripperassembled therein.

Fig. 2 is an inverted plan view of the stripper.

Fig. 3 is an enlarged sectional view of the stripper showing its contouras a free body.

Fig. 4 is a vertical sectional view of a stripper in sealing engagementwith an inner string of tubing with parts of the casing head brokenaway.

Fig.5isaviewsimiiartoFig.3showinga tubing coupling of enlarged diameterin sealing engagement with the stripper.

Referring to the drawings and more particularly to Fig. 1, ll representsa casing head or casing head attachment, arranged to be secured to thewell casing, or associated member, as by the threads II at the bottomthereof. The casing head member comprises a tubular member having aseries of bores arranged to seat or support the several elementsnecessary to complete the justed provide the proper compressive force onthe annular gland member I 9 for compressing the packing ring I, therebysealing the bore i2 of the casing head with the ring it.

Radially inward of the bolts II the upper portion of the ring it isprovided with a plurality of upwardly extending stud-bolts 20, thepositions of which are alternate with respect to the bolts it. Thesestud bolts are arranged to receive the inner gland member 2| whichcompressesthe inner packing member l5, forming a seal between the tubingl6 and the ring l3.

It should be noted that the ring l3 provides the packing seats andpacking chambers, utilizing the walls of the adjacent members withouttheir being preformed for that speciflc purpose. Again the ring I!furnishes the pressure means for both pecking members.

The bore 22, which is directly below the bore I! of the casing head, istapered to receive and hold the slim 23, the function of which is tosupport the inner concentric tubing IS in the well known manner. Thenext succeeding bores 24 and 25 are for the purpose of supporting andsecuring the flexible stripper 28 which is preferably made of rubber orthe like. The bore 25 isof smaller diameter of, which merges into thebore 29 of the lower portion of the casing head body. The bore 24 isprovided with detachable securing means for holding the stripperabutment ring 38.

3| represents a casing head vent which opens into the tubular member inthe vicinity of the bore 29. This vent is employed to convey the fluidfrom the well to places where such products may be used or diverted. Thelower bore 29 may extend to the lower end of the casing head and thecasing securing means, such as the threads Il, may be cut in the facethereof. As shown herein the lower bore 29 is provided with the innerextending portion 32 which acts as a guide for the tubing l6 and alsoprovides reenforcement for the externally threaded section II.

The casing head member is provided with the elevator lugs 33, one ofwhich is shown at the right in Fig. 1.-

Referring specifically to the stripper 26, 34 represents the lowerannular flange which is arranged to snugly fit in the pocket 21 of thecasing head. The upper annular flange 35 fits within the recess 36 ofthe stripper abutment ring 38. 31 represents castellations in the uppersurface of the abutment ring 38 which are arranged to receive a tool forturning the ring 30 to compress and hold the stripper in its properposition. In Fig. 3, the stripper 26 is shown as a free bodyin fulllines, the' dotted lines indicate the position it assumes when held inposition as shown in Fig. 1. The stripper may or may not be formed inthe shape indicated in Fig. 3, but however when assembled the body ofthe stripper between the annular shoulder 38 and the axis of pivotalmovement 39 is compressed by the abutment ring 38. This initialcompression will prevent or retard the separation of the shoulder 38from the adjacent surface of the abutment ring 30 when the skirt of thestripper is flexed downwardly and outwardly. Again, the initialcompression of the body and the stripper does not affect the shape oroperation of the skirt when the latter is required to perform itsfunction.

The upper surface 40 of the stripper between the annular flange 35 andthe shoulder 38 is formed as a mating surface to the adjacent wall 40aof the abutment ring. This surface is preferably conical and appears asa tapered surface in the drawings. This particular shape of the surface40 provides several advantages. It permits the body of the stripper andthe abutment ring 30 to be of uniform thickness, thereby providinguniform distribution of compressive and. reactive forces. Again itenhances the hinging qualities of the stripper skirt. When the skirt isforced downwardly and outwardly, hinging on the pivot point 33, theconical surface 40 does not have the tendency to abruptly leave itscomplementary surface of the abutment ring 30. If the casing head is ofthe multiple type wherein a second string of tubing is vented from abovethe stripper, any sand or grit will be unable to seek its way betweenthese mating surfaces. This is especially true if an initial compressionof the stripper body is employed, as described above, for this sectionof the stripper must be completely free from compression before it hasany tendency to leave its matng surface on the abutment ring.

A further important advantage of the surface 48 lies in its capabilityof retaining the upper portion of the stripper, thereby aiding orrelieving the load on the large annular shoulder 35. v

The skirt of the stripper is designated generally by the numeral 4|. Itcomprises a portion of the body section as designated at 42, the annulardepending section 43, the sealing contact portion 44, and the flaringnose or rim portion 45.

The zone of greatest flexibility is in the section 43 and the effectivepivotal point for hinging is at 39. The zone or body section 42contributes little to the hinging action but if the skirt is flexed tothe limit there will be a tendency for the shoulder 38 to move away fromthe abutment ring 30 unless this portion of the stripper is underinitial compression as described above. The section 44 obviouslycontributes little to the hinging action. This section must bemaintained relatively rigid to perform the sealing function. Thus theforces created by the hinging action must be transmitted to this zone toenhance the sealing effect.

46 represents a plurality of web or bracing members which are preferablyintegral with the stripper and extend from the pivotal point 39 to thetip of the nose portion 45. They may be positioned around the stripperto provide a uniform transmission and distribution of the hinging forcesfrom the section 43 to the section 44. Their number and relativethickness depends upon the size of the stripper and the degree offlexibility required to seal the varying dimensions of the tubularmembers inserted in the well. To be effective these webs must supportpart of the zone of greatest flexibility or the section 43. However itshould be noted that they are maintained relatively shallow through thissection by reason of the fact that the walls' of section 43 converge tosection 44 from whence they are maintained substantially uniform. Thedeepest sections of these webs occur opposite the tubular sealing zoneor section 45 where they become most effective. These webs function tointerconnect sections 43 and 44 and are not permitted to contact thebore of the casing head. .Their function is confined solely in bracingthese two sections.

Figs. 3, 4 and 5 illustrate the varying degrees of stressed conditionwhich the stripper undergoes from that of a free body to its applicationin effecting a seal against the coupler '41. The contour of the outeredge of the web 46 in Fig. 5 is slightly curved owing to the extremeflexure of the stripper as the coupler 41 passes therethrough. In suchinstances the hinging action is effective along the webs from the point39, causing the outer edges of the webs to assume a slight arcuatecontour.

When the well contains fluid under pressure between the casing and thetubing string [6, this pressure is effective against the back of theskirt 4| forcing it into tighter sealing engagement with the tubing l6and preventing the passage of the fluid therebetween. The fluid pressureis effective against a greater area than that of the contacting sealingsurface. This produces a concentrated sealing pressure and by reason ofthe tapered section 43 and the webs 46, which are efiective insubstantially an indirect proportion because of their relative positionand shape, the skirt is not permitted to collapse in the zone ofgreatest flexibility and the same sealing section is maintained. A skirtnot having these characteristics would collapse under high pressure,causing the rim thereof to curl outwardly, thereby losing the effectivesealing contact area, permitting an escape of the fluid until thepressure is released and it is permitted to assume its normal shape.Under high pressures such askirt may collapse and regain -its normalshape with great rapidity until it has been flexed to such an extentthat it fails completely and is torn from its socket. v

I have thus provided a stripper of relatively light cross section whichpermits repeated passage of enlarged tubing members without becomingruptured or permanently deformed and I am enabled to maintain aneflicient seal by reason of the force transmitting or bracing webs whichprevent collapse of the skirt.

'It is .evident that the fluid well pressure is effective against theentire perimetral surface of the stripper 26, including the webs l6, andthus a uniform force is effective to produce a sealing engagement forthe complete circumference of the tubing member. This is very important.

, I claim:-

1. In a well casing head structure having a tubing string disposedaxially therethrough, a flexible tubing stripper foreflecting a fluidtight seal between the head and the tubing which comprises an annularbase portion arranged to be secured in fluid tight engagement in thebore of the casing head structure, an annular body portion extendingradially inwardly and having a bore in spaced relation with the tubing,an anible tubing stripper for effecting a fluid tight seal between thehead and the tubing which comprises an annular base portion arranged tobe secured in fluid tight engagement in the bore of the easing headstructure, an annular body portion ex-' tending radially inwardly andhaving a bore in spaced relation with the tubing, an annular skirtportion extending downwardly and inwardlly of the body portion and inspaced relation with the bore of the casing head structure and thetubing, an annular sealing portion adjacent the lower end of said skirtportion for yieldably engaging the tubing string, and a plurality ofvertically disposed and circumferentially spaced ribs integral with theexterior of said skirt and sealing portions for reenforcing them as theyare flexed during the passage of members of enlarged diameter tomaintain a fluid under pressure within the casing head structure.

' AR'I'HUR. L. LEMAN.

